Abstract: The data processing system consists of a plurality of interconnected data processing subsystems one of which is a service subsystem devoted to servicing the remainder of the system and provides communication between the operator and the system to facilitate maintenance. A plurality of power supply units provide electrical power for the system, together with power supply means dedicated to the service subsystem to start up.The service subsystem includes a power adapter unit with measuring and logic circuits which cooperate with a power control microprogram to control and monitor the plurality of power supply units. The power adapter unit collects analog and digital data from the plurality of power supply units and distributes digital data to the plurality of power supply units in a multiplex mode as directed by the power control microprogram.